Although pathogenesis of IgAN is still obscure, underglycosylated IgA-containing immune-complex including IgG or IgA antibodies against the hinge region of IgA1 are key factors for IgA nephropathy. Aberrant mucosal immune response might lead to increased production of underglycosylated IgA1. It is considered that dendritic cells, Toll-like receptor (TLR)9, and cytokines interleukin-6 (IL-6), , interferon-alpha (IFN-a) and tumor necrosis factor-alpha (TNF-α), play an important role in the aberrant mucosal response.